The present invention relates to room air conditioners known as heat pumps of the reverse air cycle type shown and described in U.S. Pat. No. 4,297,854 - McCarty et al, issued Nov. 3, 1981 and assigned to the assignee of the present application. The air conditioning unit includes a solid state sensing device having a narrow temperature differential that is arranged to eliminate short cycling of the unit compressor during rapid ambient temperature rise when the unit is in the cooling mode and rapid ambient temperature drop when the unit is in the heating mode.
The application of sensing units having a narrow temperature differential is desirable in that the ambient temperature of an enclosure to be conditioned can be maintained within a degree or two of a set temperature. However, in situations where the enclosure temperature changes rapidly or within a short time, the cycling of the compressor may occur while the compression unit is still under relatively high pressure conditions. The premature starting of the compressor while appropriate relative to temperature control will, in many instances, result in failure of the compressor to start and, in isolated instances, result in compressor damage.
A general object of the present invention is to provide a room air conditioning control that has a narrow temperature differential and which is arranged to prevent short cycling of the compressor in the heating or cooling mode.
Another object of the present invention is to arrange the solid state sensor so that during the period of time immediately following the compressor deenergization, the sensor is exposed to refrigeration system heat exchanger temperature.
A fourth object of the present invention is to arrange the solid state sensor relative to the condenser and evaporator so that during the period of time immediately following compressor deenergization in the heating mode, the sensor is exposed to condenser temperature to raise the temperature sensed by the sensor and, in the cooling mode, the sensor is exposed to evaporator temperature to lower the temperature sensed by the sensor.